1. Field of the Invention
The present invention is directed to novel cyclopropane compounds, and more specifically to 2-vinyl- and 2-ethylcyclopropane-1,1-dicarboxylates, which are useful as pesticides, herbicides and as chemical intermediates.
2. Discussion of the Prior Art
Pyrethrin and various synthetic compounds modeled thereafter, such as allethrin, are widely recognized for their insecticidal activity. In view of great demand for these products and the need to modify certain properties of these products to make them adaptable for other uses, much effort has been directed to the synthesis of structurally related compounds, i.e., compounds based on the 2-vinylcyclopropane structure.
Lower alkyl 2-vinylcyclopropane-1,1-dicarboxylates are reported. For example, Kierstead et al. (J. Chem. Soc., 1952, 3610-21 and J. Chem. Soc., 1953, 1799) report the preparation of diethyl 2-vinylcyclopropane-1,1-dicarboxylate by the condensation of 1,4-dibromo-2-butene and ethyl sodiomalonate. Heretofore known 2-vinylcyclopropane-1,1-dicarboxylates have, however, been limited to the simple ester products, i.e., lower alkyl esters, due to the limitations of the malonic ester condensation procedure by which the products are obtained and the instability of the compounds due to the presence of gem carboxyl groups. The tendency of gem carboxyl groups to dicarboxylate at elevated temperatures is well known.